You might like this website: https://www.ambient-mixer.com/

Safe as in encrypted and/or authenticated? Not at all! I only do this on networks I fully trust and with files that are not too sensitive. But it’s quick and easy to set up. All my machines have python installed so hence the idea.

I often spin up a quick python http server. Just go to the folder which has the files you want to transfer and run the following command: python3 -m http.server. This will server the folder content Serving HTTP on 0.0.0.0 port 8000 (http://0.0.0.0:8000/) .... On your phone you can then browse to http://PC_IP:8000 and download what you want/need.